This invention relates generally to mammography, and more particularly, to an apparatus and method for readily obtaining and processing tomosynthesis data for x-ray examination of a patient""s breasts.
Mammography is a low-dose x-ray procedure that creates one or more images of a patient""s breasts desirable for detection of early stages of cancer. FIG. 1 illustrates one example of a prior art mammography machine 10. Mammography machine 10 generally includes an x-ray tube 12 attached to an arm 14, which arm 14 is pivotally attached to a support 16, and a film plate 18 attached to an arm 20, which arm 20 is also pivotally attached to support 16. X-ray tube 12 and arm 14, and film plate 18 and arm 20, are counterbalanced so that x-ray tube 12 and film plate 18 may be easily manually pivoted, upwardly and downwardly, and locked in position at different angular orientations.
A typical mammography procedure takes approximately thirty minutes. The procedure generally includes obtaining two images of each of the patient""s breasts, one from above and one from the side. For example, separate images are obtained of each of the patient""s breasts with x-ray tube 12 and film plate 18 disposed in a vertically orientated arrangement along axis A (i.e., cranial-caudal) as shown in FIG. 1. In addition, separate images are obtained of each the patient""s breasts with x-ray tube 12 and film plate 18 oriented on an angle, e.g., along axis B1 (i.e., medio-lateral oblique) for one of the patient""s breasts, and along axis B2 for the patient""s other breast.
During the procedure, the patient""s breast is compressed between a compression paddle 22, e.g., a piece of plastic, and film plate 18 to flatten the breast making the breast easier to be imaged. In obtaining the images, either from above or from the side, x-ray tube 12 is aligned perpendicular or normal to film plate 18. A physician or radiologist then reviews the images of the breast, i.e., mammograms, to identify any breast cancer.
While the above described procedure is one of the best methods of detecting early forms of breast cancer, it is still possible for the detection of breast cancer to be missed by a physician or radiologist reviewing the mammograms. For example, breast cancer may be missed by being obscured by radiographically dense, fibroglandular breast tissue.
Tomosynthesis breast imaging, in which a plurality of images are acquired as the x-ray source is moved in an arc relative to a stationary digital detector, has been studied in an effort to detect early forms of breast cancer. By shifting and adding the plurality of images, it is possible to reconstruct any plane in the breast being imaged that is parallel to the detector.
Numerous drawbacks have prevented the widespread implementation of tomosynthesis breast imaging. For example, the procedure requires in combination, an x-ray source that limits x-ray exposure to the patient and a digital x-ray detector. Also, the procedure requires that the digital x-ray detector and the patient""s breast be maintained in a stationary or fixed position while the x-ray tube is moved and positioned for obtaining the plurality of images.
Therefore, there is a need for an apparatus and method for implementing tomosynthesis breast imaging in which an x-ray source is quickly and smoothly moved and positioned relative to an x-ray detector to obtain a plurality of images of a patient""s breast.
An apparatus and method are provided for obtaining tomosynthesis data of an object such as a patient""s breast in which the apparatus includes a radiation source, a radiation detector, and an actuator operably connectable to the radiation source. The actuator is operable to controllably allow the radiation source to move under the influence of gravity from a first position to a second position relative to the radiation detector, wherein radiation emitted by the radiation source at a plurality of positions between the first position and the second position and passing through the object is detectable by the radiation detector.